Existing stethoscopes are currently utilized to auscultate or listen to physiologic sounds within the body. Auscultation with existing stethoscopes is currently performed by intermittently applying a stethoscope to the body surface through which the clinician hears various sounds. Intermittent auscultation may be a relatively benign procedure. However, several disadvantages and hazards are associated with the use of existing stethoscopes. First, patients undergoing surgery may have the sterile field invaded thereby risking infection in order for the clinician to auscultate the chest. Another disadvantage of known stethoscopes is that patients are frequently awakened and disturbed so that the clinician may apply a cold stethoscope to the patient's chest to monitor vital signs. Recent studies have shown serious developmental abnormalities in newborn infants who are frequently disturbed to auscultate heart and lung sounds with known stethoscopes. Another disadvantage of existing stethoscopes is that the quality of sound wave transmission is dependent upon an airtight seal between the stethoscope and the skin. In the absence of an airtight seal, background noise is inadvertently detected and physiologic sound transmission is impaired. Finally, another disadvantage of existing stethoscopes is that they are not capable of generating positive or constructive interference of physiologic sound waves.
Stethoscopes are known which use two sound receiving heads but have several disadvantages. The stethoscope shown in U.S. Pat. No. 4,706,777 to Baumberg discloses a stethoscope with two sound transmitting tubes connected to a valve. Depending upon the position of the valve, the clinician receives either mono or stereo sounds. However, even when receiving stereo sounds, the sound picked up by each sensor is transmitted through separate channels. In contrast, the present invention transmits sounds through a common tube with constructive interference of sound waves resulting.
Other patents show stethoscopes with multiple heads. In the Patents to Cefaly (U.S. Pat. No. 3,124,211) and Tynan (U.S. Pat. No. 2,722,989), the sound receiving heads are not capable of being used simultaneously. In the patents to Zala (U.S. Pat. No. 1,853,951), Bodenger (U.S. Pat. No. 3,144,091) and Hardt (U.S. Pat. No. 1,847,607), the sound receiving heads transmit sounds through separate tubes.
Finally, the Patent to Tailor et al. (U.S. Pat. No. 4,401,125) discloses a stethoscope securing pad which includes an adhesive surface for securing the head of the stethoscope to the patient's skin. However, this pad is larger than the diaphragm head and has only one adhesive surface. Also, it does not appear to form an airtight seal between the stethoscope head and the skin.